The new cultivar was discovered as a result of a planned breeding program directed by the inventors, Anthony Robin White and Susan Barbara White, citizens of the United Kingdom. The seed parent is an unnamed, unpatented plant of Rhodanthemum hosmariense and the pollen parent is an unpatented variety of Rhodanthemum plant, of unknown species. The cross resulting in ‘CASABLANCA’ was made June 2004. The new variety was discovered during the Spring of 2008, by the inventors in a commercial nursery in Hampshire, United Kingdom.
Asexual reproduction of the new cultivar ‘CASABLANCA’ by vegetative cuttings was first performed in 2008, at a commercial nursery in Hampshire, United Kingdom. Multiple generations have since been produced and have shown that the unique features of this cultivar are stable and reproduced true to type in successive generations.